Variable condenser



W. DUBILIER.

VARIABLE CONDENSER.

APPLICATION HLED JULY25, 1911. RENEWED FEB. 2, 1921,

i ,396,0.30. Patented Nov. 8, 1921.

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WILLIAM DUBILIER, OF NEW YORK, N. Y.

VARIABLE CONDENSER.

Specification of Letters Patent.

Application filed July 25, 1917, Serial K0. 182,796. Renewed February 2,1921. Serial No. 441,992.

To all 20110111. 2'!- muy concern.

Be it known that I, VILLIAM DUBILIER, of Xew York, in the county of NewYork. and in the State of New York. have invented a certain new anduseful Improvement in Variable Condensers. and do hereby declare thatthe following is a full. clear. and exact description thereof.

My invention relates tocondensers. and has for an object to produce sucha device which shall possess extreme flexibility of adjustment to assumeany capacity between any desired limits.

Another object of my invention is to design such a condenser to permitthe adjustment to be made without breaking the circuit in which thecondenser is contained.

Other objects of my invention are to provide such an apparatus whichshall be light in weight. require but small space. be economical tomanufacture. and in which there shall be but slight possibility ofchanges in the capacity of the elements of the condenser with continueduse. 1

Other objects of my invention will be in part obvious and in partspecifically mentioned hereinafter.

In the drawings. in which I have shown an embodiment of my inventionwhich is to be considered merely as typical of the principle thereof, 1

igure 1 is a plan view of the condenser:

Fig. 2 is a section On line AA. Fig. 1, with the central portion of thebase cut away. and

Fig. 3 is a diagrammatic representation of the circuit connections ofthe device.

The different elements of the condenser are supported upon an insulatingbase 1 which may be made of bakelite. or other similar material. [*ponthis base 1 are mounted a series of contacts 2. which may convenientlybe mounted in a circle thereupon. as shown in Fig. 1. A series ofcondensers 3. 4. 5. etc.. are located adjacent the shown in Fig. 2. maybe supported from said base by means of a sector 6. later to bedescribed. Condensers 3. 4 and 5. in the simple arrangement illustrated,are of fixed capacities, having a common difi'erence in capacity, andone terminal of each of said condensers is placed in circuit Y with acontact 2 by means of connections 7.

A contact arm 8 is mounted upon a s indle 9, and may be moved to engageany esired .etual to the length denser is positioned contact by means ofa suitable handle 10. One terminal 11 of the condenser is electricallyconnected with the spindle 9. and through said spindle with contact arm8, by wire 12. which wire is embedded in the insulating base 1. In thisway terminal 11 of the condenser may placed in circuitwith any desiredfixed condenser 3, 4, 5 by adjustment of the contact arm 8.

To obtain a capacity of the device which is intermediate the capacityvalues of the fixed condensers t and 5, I employ a variable condenserhaving as a stationary element,thesector 6. On the form shown in thedrawings. this sector 6 is a semi-circular member made-of aluminum orsimilar material. and is slotted at 13 to accommodate the movableelement of the variable condenser. This movable condenser elementcomprises a thin semi-circular plate 14. carried by a rotatable shaft15. which shaft is suitably journaled in the insulating base 1. Thevariable condenser formed by elements 6 andH isdesignedto have a maximumcapacity substantially equal'to the common Patented Nov. 8, 1921. i

ditl'erence in capacity between fixed conof the variable condenser makesone complete revolution each time the spindle 9 is turned to morecontact arm 8 a distance of one of thecontacts 2. ovable element 14 ofthe variable conon the shaft 15 so as to be entirely removed from slot13 when contact arm 8 has just passed from one contact 2 to the adjacentportion of the next contact. From this construction it follows that. ascontact arm capacity of the variable condenser will increase from zero.reaching a maximum when arm 8 is engaging the central portion of thecontact. and decreasing again to zero as arm 8 passes from such centralposition to the remaining edge of the contact. 7

The remaining condenser terminal 18 is mounted upon sector 6, whichsector is alsoventr continuous tween terminal 11 and removable plate 8pames over a contact 2, the

14. Intermittent connection between these elements is, however, providedby means of a switch arm 21 which is mounted upon shaft 15, and whichengages a semi-circular fixed contact 22. This contact 22 is separatedfrom sector 6 by insulation 23, and is in circuit with terminal 11through a wire 24, and wire 12. Contact 22 is semi-circular so thatswitch arm 21 engages this contact as longas plate 14 is entering slot13, but leaves contact 22 as soon as plate 14 begins toemerge from saidslot, thus throwing the variable condenser out of circuit after it hasreached its maximum capacity.

In the use of-my invention the base 1 may be marked adjacent thecontacts 2, to indicate the capacities of the fixed condensersconnectedrespectively to such contacts. To adjust the condenser to anydesired capacity, contact arm 8 will be moved to engage the contact 2which is connected to the condenser which has the fixed capacity nextlower than the desired capacity; as the arm 8 is moved across thecontact, gears 16 and 17 will be rotated to adjust the variablecondenser to a capacity equal to the difference between thedesiredcapacity and the capacity of the fixed condenser which isconnected to the contact 2. If it is desired to increase the capacitystill further, contact arm 8 will be moved toward the adjacent fixedcontact which is connected to the condenser of next higher value, afterwhich the variable condenser can be adjusted to obtain any desiredcapacity between the value of the corresponding fixed condenser and thatof the fixed condenser of still higher capacity.

From the above description it follows that any desired capacity betweenthe limits of the capacities of the fixed condensers, may be obtainedmerely by movement of the arm 8 over the fixed contacts 2. As thevariable condenser is of a small capacity relative to the range of thewhole device, a fine adjustment' is also possible. Such adjustment mayalso be made without breaking the circuit in which the condenser iscontained. since contact arm 8 is always in engagement with one or theother of the fixed contacts 2.

If a variable condenser alone is employed to furnish the desiredvariable capacity, it is liable to happen that, owing to the number ofsectors and plates necessary to be employed, the capacity of thecondenserfor a given position of the plates, does not remain constant.This is due to the fact that, during continued use. and handling or wearof the condenser, the lates and sectors shift or warp from their initialrelation to each other. Furthermore, a fixed condenser, although notsubject to the above disadvantage, has the disadvantage that onlycertain definite capacities can be obtained. In ap-' having a.

able condenser, and yet the capacity of the condenser is practicallyconstant, since the 1112.]01 fraction of each capacity value is suppliedby a fixed condenser, and a variable condenser with very few parts toget out of order is employed, and even if the plate of such condensershifts or warps relative to the sector, only a very small error will beintroduced, since only the capacity of the variable condenser isafiected, and such ca acity is relatively small in value.

The 'ypes of condensers and switches above described are not essentialto the invention, and the preferable, are but illustrative.

I claim 1. In combination, a series of fixed condenser units having. acommon difierence in capacity, a variable condenser having a maximumcapacity substantially equal to said common difference, and means forinserting in circuit with any of said units any desired fraction of thecapacity of said variable condenser, said variable condenser being ofsmall capacity relative to the range of the ose of a variformsdescribed, although whole condenser, and including but few rela- 2. Incombination, a series of fixed con-.

denser unitshaving a common difference in capacity, a switch forselectively'throwing said units in circuit, a variable condenser havinga maximum ca acity substantially equal to said common difierence, andmeans for inserting in said circuit any desired fraction of the capacityof said variable condenser, said variable condenser beinglof smallcapacity relative to the range of t e whole condenser, and including butfew relatively movable parts, whereby errors due to changes in thevariable condenser are minimized.

3. In combination, a series of fixed condenser unitshaving a commondifference in capacity, spectively to said units, a switch membermovable over said contacts to connect any desired unit in circuit, avariable condenser maximum capacity substantially equal to. said commondifference, and means connected to said switch for inserting in circuitany desired fraction of the capacity of said variable condenser, as saidswitch moves 'over a contact, said variable condenser being a series ofcontacts connected reable over said contacts to connect any desired unitin circuit. a. variable condenser having an element angular-1yadjustable to a capacity equal to said common difference, and gearingconnected to said rotary switch and element for inserting in circuitvarying fractions of the capacity of said variable con denser, as saidswitch moves over a contact, said variable condenser being of smallcapacity relative to the range of the whole condenser, and including butfew relatively movable parts. whereby errors due to changes in thevariable condenser are minimized.

5. In combination, a series of fixed condenser units having a commondifference in capacity, a series of contacts connected respectivelytosaid units, a rotary switch movable over said contacts to connect anydesired unit in circuit, a variable condenser comprising a slottedsector. a spindle carrying a sector-like plate movable in said slot,said spindle being geared to said rotary switch. said variable condenserbeing of small capacity relative to the range of the whole condenser,and including but few relatively movable parts. whereby errors due tochanges in the variable condenser are minimized.

6. In combination, a pair of fixed condenser units of differentcapacities, a variable condenser, and means for throwing into circuitany one of said units and any desired fraction of the capacity of saidvariable condenser, while maintaining a closed circuit condition at alltimes, said variable condenser being of small capacity relative to therange of the whole condenser, and including but few relatively movableparts, whereby errors due to changes in the variable condenser areminimized.

7. In combination, a series of fixed condenser units having a commondifference in capacity, a variable condenser having amaximum capacitysubstantially equal to said common difference, and means for throwinginto circuit any one of said units and any desired fraction of thecapacity of said variable condenser, while maintaining a closed circuitcondition at all times. said variable condenser being of small capacityrelative to the range of the whole condenser, and including but fewrelatively movable parts,

prising a plurality units having a common difference in capac capacity.a base whereby errors due to changes in the variable condenser areminimized.

8. In combination a fixed condenser comprising a plurality of separateand distinct units having a common difference in capacity,switchingmeans for selectively placing said units in circuit includingcontacts respectivelyconnected to said units and a contact armselectively engageable with said contacts, a variable condenser incircuit with said fixed condenser, and a common operating means forshifting said variable condenser and said contact arm. I

9. In combination a fixed condenser comof separate and distinct ity,switching means for selectively placing said units in circuit includingcontacts arranged in circular fashion, a contact arm located centrallywith regard to said contacts, said contact arm being selectivelyengageable with said units,.a variable condenser in circuit with saidfixed condenser including a rotatable movable element, and a commonrota-table opera-ting member for shifting said contact arm and therotatable element of said variable condenser.

10. In combination a fixed condenser in eluding units having a commondifference in plate carrying contacts respectively connected to saidunits, a rotary switch arm centrally disposed with respect to saidcontacts, a variable condenser secured to said base plate, and a rotaryshaft journaled within said base plate adapted to actuate saidcontactarm and the movable element of said variable condenser.

11. In combination a fixed condenser including units having a commondifference in capacity, a base plate carrying contacts respectivelyswitch arm centrally disposed with respect to said contacts, a variablecondenser secured to said base plate and interposed between the same andsaid fixed condenser, and a rotary shaft passing through said base lateadapted to actuate said contact arm an the movable element'of saidvariable condenser. In testimony that I claim the foregoing I havehereunto set my hand.-

WILLIAM DUBILIER.

connected to said units, a rotary I

